Coliform Bacteria Testing At Home: The Do’s and The Don’ts

Health authorities strongly recommend annual coliform bacteria testing for private water wells as contamination can occur without any change in taste or odor to the water. Depending on your needs, there are many options available for coliform bacteria testing, ranging from testing yourself at home to EPA-certified, lab quality testing.

There are many ways that well water can become contaminated by coliform bacteria, so it is most important to test:

  • Once a year for all private residential water wells
  • After a new well has been constructed
  • After recent work has been done on the well
  • If you suspect or see any indication that contamination has occurred due to interaction with flood water

Coliform Bacteria Test Kits:

The “Coliform Bacteria EZ Cult 24 Hour” test kit is an effective, do-it-yourself coliform test that can verify the presence of coliform bacteria in your water. It is EPA compliant, but is NOT state certified or licensed. If you are testing your water after a new home purchase, the bank may require a state licensed lab test. In this case you would need certified lab test results.When using the “EZ Cult” test, the media turns blue-green when coliform bacteria are present. E. coli, a type of coliform bacteria, requires a separate, more specific test. It is confirmed by blue fluorescence under UV light.
For cheap and easy lab quality testing, we recommend the WaterCheck: Quick Coliform Test. This test will test for the presence or absence of coliform and E.coli bacteria, and will fax the preliminary test results back to you in two business days.

For more extensive or state required testing (such as applying for a new day care center license or a bank loan), we recommend the WaterCheck test, as it will yield EPA-certified laboratory results for a fraction of the cost of regular laboratory testing.

How To Collect A Water Sample For The WaterCheck Test:

1. Wash your hands with soap and warm water.

2. Take the sample from a cold water tap. Make sure to use a tap without a screen or remove the screen before you collect the sample.

3. Let the cold water run constantly for at least 2 minutes before you collect the sample.

4. Hold the bottle near the base of the tap to collect the sample. Fill it past the 200 milliliter mark (the shoulder of the bottle). Do not overfill the bottle.

5. Put the cap on the bottle immediately after filling. Make sure the cap is secure, but do not over-tighten it.

6. Put the identification label from the requisition form on the bottle.

Once You Have Collected Your Sample:
Fill out the requisition form and include the information below. If you miss anything on the requisition, your sample might not be processed.

  • Name and daytime phone number
  • Mailing address and postal code
  • Collection site (e.g., kitchen sink)
  • Legal land description and/or civic address
  • Date and time sample was collected
  • Name of person who collected the sample

On the requisition form, write down if this is a re-sample. You also need to fill out section A (Drinking Water) and add any comments or special requests at the bottom of the requisition.

  • Put the sample and requisition form in the plastic bag that came with the sample bottle.
  • Put the sample in a cooler filled with ice packs and bring it to a drop-off location near you right away, or if sending by express, use overnight next day/morning option.

Double Check: Samples must be collected from the cold water supply line.

Important! Do Not:

  • Rinse the sampling bottle
  • Let water overflow or splash down the side of the bottle
  • Put the cap on a counter-top (it can get contaminated)
  • Open the bottle until you are ready to collect your sample
  • Touch the inside of the cap, mouth, or neck of the bottle
  • Collect samples from a garden hose, outside tap, or other place that might be dirty


Good luck with your test! View our Bacteria information page if you would like more information about coliform bacteria and removing it from your well water. If you have any further questions, or would like to update us on your progress – we love pictures and testimonials! – you can reach us at or on Facebook.

About the Author Gerry Bulfin

Need help with your well water? I have been assisting homeowners, small communities and businesses improve their well water quality since 1989. Please email me at if you have a question about water testing, test kits or well water systems in general. Gerry Bulfin CWS-IV Master Water Specialist WQA Certified Licensed California Water Treatment Contractor